Fluid injection valves are in widespread use, in particular for an internal combustion engine where they may be arranged in order to dose fuel into an intake manifold of the internal combustion engine or directly into the combustion chamber of a cylinder of the internal combustion engine.
Injection valves are manufactured in various forms in order to satisfy the various needs for the various combustion engines. Therefore, for example, their length, their diameter, and all the various elements of the injection valve being responsible for the way the fluid is dosed may vary in a wide range. In addition to that, injection valves can accommodate an actuator for actuating a needle of the injection valve, which may be, for example, an electromagnetic actuator or a piezoelectric actuator.
In order to enhance the combustion process in view of degradation of unwanted emissions, the respective injection valve may be suited to dose fluids under high pressures. The pressures may be in case of a gasoline engine, for example, in the range of up to 500 bar, and in case of a diesel engine, in the range of 2500 bar, and above.
In addition, in order to enhance the combustion process and/or to reduce the risk of malfunction, an injection valve normally comprises a fuel filter for filtering the fluid, and it also may comprise an adjusting member for adjusting the maximal load of a calibration spring of the injection valve. Filtering the fuel is necessary for keeping possible impurities of the fuel off from the needle and off from the injection nozzle. For these purposes it is known to provide a so-called adjusting fuel filter assembly comprising three parts: a frame, a bush, and a screen. Such an adjusting fuel filter assembly cooperates with a spring, which preloads the valve needle.